An ice pick with 563 ft/lbs is still an ice pickRemember: we are talking early 1990's - the birth of the 300 Whisper. Some special forces guys were complaining to JD over dinner about having to "double tap" bad guys with their MP5's in order to put them down decisively. JD's answer was the 300 Whisper on an AR platform. One subsonic replacing another subsonic. Any supersonic capabilities of the 300 Whisper was just icing on the cake - but not its primary mission. Although the diameter of the 30 cal. bullet (.308) is smaller than the 9mm bullet (.355), its increased weight allows it to deliver more punch:
147 gr. @ 1,050 fps = 360 ft/lbs of energy at the muzzle
230 gr. @ 1,050 fps = 563 ft/lbs of energy at the muzzle
That is a substantial increase. leaves the 9mm in the dust.